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The present invention concerns a keyboard support for movably supporting
a keyboard with respect to a work surface of a workstation. The keyboard
support includes a workstation engaging member adapted to be attached to
an underside of the work surface, a keyboard engaging member for
supporting a keyboard, and a linkage assembly mechanically coupling and
providing relative movement between the workstation engaging member and
the keyboard engaging member and thereby between the keyboard and the
work surface. The keyboard support also includes a braking assembly
adapted to allow relative movement of the keyboard engaging member with
respect to the workstation engaging member in an unlocked position and to
prevent relative movement of the keyboard engaging member with respect to
the workstation engaging member in a locked position. The braking
assembly comprises a roller assembly carried on a connector of the
linkage assembly. The roller assembly is biased against a wedge affixed
to a vertical side of the keyboard engaging member.

15. A keyboard support for movably supporting a keyboard with respect to
a work surface of a workstation comprising: a) a workstation engaging
member adapted to be attached to an underside of the work surface; b) a
keyboard engaging member disposed forwardly of the workstation engaging
member for supporting a keyboard including spaced apart sides defining
aligned slots and aligned holes; c) a linkage assembly mechanically
coupling and providing relative movement between the workstation engaging
member and the keyboard engaging member, the linkage assembly including:
1) an upper support member including one end rotatably mounted to the
workstation engaging member and further including an arcuate slot and a
hole at an opposite end; 2) a lower support member including one end
rotatably mounted to the workstation engaging member and further
including a hole at an opposite end; 3) a lower connector passing through
the arcuate slot in the upper support member, the aligned slots of the
keyboard engaging member, and the hole passing through the lower support
member; and 4) an upper connector passing through the aligned holes of
the keyboard engaging member and the hole of the upper support member; d)
a tilt lockout member rotatably coupled to an end of the lower connector
and including an arm adapted to fit into one of the aligned slots of the
keyboard engaging member, the tilt lockout member to position the arm in
a selected one of a first and a second position, in the a first position,
the arm being disposed in the one of the aligned slots of the keyboard
engaging member on one side of the lower connector and in the second
position, the arm being disposed in the one of the aligned slots of the
keyboard engaging member on an opposite side of the lower connector, in
the first position, pivoting of the keyboard engaging member in a
positive tilt angle direction a is restricted by the arm and in the
second position, pivoting of the keyboard engaging member in the positive
tilt angle direction is not restricted.

16. The keyboard support of claim 15 wherein in the first position of the
tilt lockout member, a maximum positive tilt angle of the keyboard
engaging member is substantially 0 degrees and in the second position,
the a maximum positive tilt angle of the keyboard engaging member is
substantially 10 degrees.

17. The keyboard support of claim 15 wherein the end of the lower
connector that the tilt lockout member is coupled to includes an enlarged
head and the tilt lockout member is carried by the connector and bears
against the enlarged head.

18. The keyboard support of claim 15 wherein a tilt adjustment knob is
threaded onto a threaded end of the lower connector opposite the end of
the lower connector that the tilt lockout member is coupled to.

19. A keyboard support for movably supporting a keyboard with respect to
a work surface of a workstation comprising: a) a workstation engaging
member adapted to be attached to an underside of the work surface
including a clevis having first and second spaced apart substantially
vertical sides; b) a keyboard engaging member disposed forwardly of the
workstation engaging member for supporting a keyboard including spaced
apart substantially vertical sides defining aligned slots and aligned
holes; c) a linkage assembly mechanically coupling and providing relative
movement between the workstation engaging member and the keyboard
engaging member, the linkage assembly including: 1) an upper support
member including a hole at one end for rotatable mounting to the
workstation engaging member clevis; 2) a lower support member including a
hole at one end for rotatable mounting to the workstation engaging member
clevis; 3) a first connector mounted between the sides of the clevis and
passing through the hole of the upper support member; 4) a second
connector mounted between the sides of the clevis and passing through the
hole of the lower support member; 5) a third connector affixed to the
upper support member; d) a spring counterbalance assembly including a
first spring wound around the first connector, a first end of the first
spring bearing against the third connector and applying a spring torsion
force to pivot the upper support arm upwardly, a second end of the first
spring being insertable into a selected one of a plurality of openings in
the first side of the clevis, a magnitude of the spring torsion force
dependent on which of the plurality of openings the first spring is
inserted into.

20. The keyboard support of claim 19 wherein the first side of the clevis
includes three openings, vertically spaced apart, when the second end of
the first spring is inserted into the vertically highest opening, the
spring torsion force being a low magnitude, when the second end of the
first spring is inserted into the vertically middle opening, the spring
torsion force being an intermediate magnitude, and when the second end of
the first spring is inserted into the vertically lowest opening, the
spring torsion force being a high magnitude.

21. The keyboard support of claim 19 wherein the spring counterbalance
assembly further includes a second spring wound around the first
connector, a first end of the second spring bearing against the third
connector and a second end of the second spring fixed with respect to the
clevis, the second spring applying a spring torsion force to pivot the
upper support arm upwardly.

22. The keyboard support of claim 18 wherein rotation of the tilt
adjustment knob with respect to the threaded end of the lower connector
in a first direction changes a tilt angle of the keyboard engaging member
in the positive tilt angle direction and rotation of the tilt adjustment
knob with respect to the threaded end of the lower connector in an
opposite, second direction changes the tilt angle of the keyboard
engaging member in a negative tilt angle direction.

23. The keyboard support of claim 22 wherein the first direction is a
direction of rotation of the tilt adjustment knob that unthreads the tilt
adjustment knob from the threaded end of the lower connector, the
keyboard engaging member pivoting in the positive tilt angle direction.

24. The keyboard support of claim 22 wherein the second direction is a
direction of rotation of the tilt adjustment knob that threads the tilt
adjustment knob onto the threaded end of the lower connector, the
keyboard engaging member moving in the negative tilt angle direction.

25. The keyboard support of claim 15 wherein the keyboard engaging member
pivots about the upper connector.

26. The keyboard support of claim 22 wherein rotation of the tilt lockout
member in the first direction permits the arm of the tilt lockout member
sufficient clearance with respect to the keyboard engaging member to be
moved between the first position and the second position.

27. The keyboard support of claim 18 wherein the tilt lockout member is
affixed to the end of the lower connector and rotates with the lower
connector to move between the first position and the second position.

28. A keyboard support for movably supporting a keyboard with respect to
a work surface of a workstation comprising: a) a workstation engaging
member adapted to be attached to an underside of the work surface; b) a
keyboard engaging member disposed forwardly of the workstation engaging
member for supporting a keyboard including spaced apart sides defining
aligned slots and aligned holes; c) a linkage assembly mechanically
coupling and providing relative movement between the workstation engaging
member and the keyboard engaging member, the linkage assembly including:
1) an upper support member including one end rotatably mounted to the
workstation engaging member and further including an arcuate slot and a
hole at an opposite end; 2) a lower support member including one end
rotatably mounted to the workstation engaging member and further
including a hole at an opposite end; 3) a lower connector passing through
the arcuate slot in the upper support member, the aligned slots of the
keyboard engaging member, and the hole passing through the lower support
member; and 4) an upper connector passing through the aligned holes of
the keyboard engaging member and the hole of the upper support member; d)
a tilt lockout member coupled to an end of the lower connector and
including an arm adapted to fit into one of the aligned slots of the
keyboard engaging member, the tilt lockout member movable to position the
arm in a first position wherein the arm is disposed in the one of the
aligned slots of the keyboard engaging member on one side of the lower
connector, in the first position, pivoting of the keyboard engaging
member in a positive tilt angle direction being restricted by the arm.

29. The keyboard support of claim 28 wherein the tilt lockout member is
movable to position the arm in a selected one of the first position and a
second position, in the first position, the arm being disposed in the one
of the aligned slots on the one side of the lower connector and, in the
second position, the arm being disposed in the one of the aligned slots
on an opposite side of the lower connector, in the first position,
pivoting of the keyboard engaging member in the positive tilt angle
direction is restricted by the arm and in the second position pivoting of
the keyboard engaging member in the positive tilt angle direction is not
restricted.

30. The keyboard support of claim 28 wherein the end of the lower
connector that the tilt lockout member is coupled to includes an enlarged
head and the tilt lockout member is carried by the connector and bears
against the enlarged head.

31. The keyboard support of claim 28 wherein a tilt adjustment knob is
threaded onto a threaded end of the lower connector opposite the end of
the lower connector that the tilt lockout member is coupled to.

32. The keyboard support of claim 31 wherein rotation of the tilt
adjustment knob with respect to the threaded end of the lower connector
in a first direction changes a tilt angle of the keyboard engaging member
in the positive tilt angle direction and rotation of the tilt adjustment
knob with respect to the threaded end of the lower connector in an
opposite, second direction changes the tilt angle of the keyboard
engaging member in a negative tilt angle direction.

33. The keyboard support of claim 32 wherein the first direction is a
direction of rotation of the tilt adjustment knob that unthreads the tilt
adjustment knob from the threaded end of the lower connector, the
keyboard engaging member pivoting in the positive tilt angle direction
and further wherein the second direction is a direction of rotation of
the tilt adjustment knob that threads the tilt adjustment knob onto the
threaded end of the lower connector, the keyboard engaging member
pivoting in the negative tilt angle direction.

34. The keyboard support of claim 28 wherein the keyboard engaging member
pivots about the upper connector.

35. The keyboard support of claim 31 wherein rotation of the tilt lockout
member in the first direction permits the arm of the tilt lockout member
sufficient clearance with respect to the keyboard engaging member to be
moved between the first position and the second position.

Description

FIELD OF THE INVENTION

[0001] The present invention relates to a keyboard support attachable to
an underside of a workstation work surface and, more particularly, to a
keyboard support providing both height and tilt adjustment of a keyboard
with respect to the work surface.

BACKGROUND OF THE INVENTION

[0002] Various keyboard support designs have been proposed for movably
supporting a computer keyboard which is part of a computer workstation.
Generally, the workstation includes a work surface that supports a
computer monitor. The keyboard support typically includes a workstation
engaging member, a keyboard engaging member, and a mechanical linkage
between the workstation engaging member and the keyboard engaging member.

[0003] The workstation engaging member is attached to an underside of the
work surface and the keyboard engaging member supports a planar keyboard
support surface on which the keyboard is disposed. The linkage permits
relative movement of the keyboard engaging member with respect to the
workstation engaging member.

[0004] For ergonomic reasons, it is desirable the keyboard support surface
be adjustable both in terms of vertical position or height and
orientation or tilt angle with respect to the work surface. Various
designs have been proposed for keyboard supports wherein the keyboard
support surface has both height and tilt angle adjustability with respect
to a work surface. One such design is disclosed in U.S. Pat. No.
6,450,467 to Timm, which is assigned to the assignee of the present
invention. The '467 patent is incorporated herein in its entirety by
reference. Other examples of keyboard supports include the supports
disclosed in U.S. Pat. Nos. 5,145,136 to McConnell and 5,881,984 to Lin.

[0005] One area of continuing attention and potential improvement is that
of the braking assembly of a keyboard support. The braking assembly of a
keyboard support allows a user of the keyboard support to move the
keyboard support surface (and thereby the keyboard) to a desired height
relative to the work surface and then lock the support at the desired
height. The braking assembly may also allow the user to adjust the tilt
angle of the keyboard support surface. The braking mechanism must be easy
to use allowing a user to easily adjust the keyboard support surface to a
desired height and, at the same time, must have a positive locking
capability such that once the keyboard support surface is at the desired
height and in the locked position, pressure applied to the keyboard
during use will not cause the support to move.

[0006] Additionally, the braking mechanism must be rugged, since the
keyboard support surface extends outwardly and away from the workstation
work surface and, therefore, is prone to being hit or bumped by the user
or others in the area. Further, the keyboard support must be durable.
While a user may expect his or her computer system to be replaced every
few years because of technological advances, a user will generally expect
a keyboard support to last for many years. Finally, since a keyboard
support is an extra cost, add-on feature to most computer workstations,
it must be economical and cost-effective to manufacture such that the
keyboard support can be competitively priced.

[0007] What is needed is a keyboard support that permits vertical height
and tilt adjustment of the keyboard support surface. What is also needed
is a keyboard support with a braking assembly that provides easy vertical
adjustment of the keyboard support surface and positive locking of the
support surface once a desired height is ascertained. What is also needed
is keyboard support wherein the braking assembly is durable. What is also
needed is a keyboard support that is cost efficient to manufacture.

SUMMARY OF THE INVENTION

[0008] The present invention concerns a keyboard support for movably
supporting a keyboard with respect to a work surface of a workstation. In
one illustrated embodiment, the keyboard support includes a workstation
engaging member adapted to be attached to an underside of the work
surface, a keyboard engaging member for supporting a keyboard, a linkage
assembly mechanically coupling and providing relative movement between
the workstation engaging member and the keyboard engaging member and
thereby between the keyboard and the work surface, and a braking assembly
adapted to allow relative movement of the keyboard engaging member with
respect to the workstation engaging member in an unlocked position and to
prevent relative movement of the keyboard engaging member with respect to
the workstation engaging member in a locked position.

[0009] The keyboard engaging member includes a generally planar keyboard
support surface whose position and orientation are controlled to control
a position and orientation of the keyboard with respect to the work
surface of the workstation. The keyboard engaging member includes two
parallel side pieces spaced apart by and extending rearwardly from a
center section. Extending above the center section is the keyboard
support surface. The side pieces define aligned slots on opposite sides
of the center section and aligned holes on opposite sides of the center
section wherein the aligned holes are disposed vertically above the
aligned slots.

[0010] The workstation engaging member is attachable to an underside of
the work surface and includes two parallel side pieces spaced apart by a
center section.

[0011] The linkage assembly includes a first support member having one end
rotatably mounted to the workstation engaging member and including a body
portion that extends away from the workstation engaging member at a
controlled angle. The first support member includes an arcuate slot and a
hole spaced from the arcuate slot at an end spaced from the end that is
rotatably mounted to the workstation engaging member.

[0012] The linkage assembly further includes a second support member
having one end rotatably mounted to the workstation engaging member and
including a body portion that extends away from the workstation engaging
member at a controlled angle. The second support member includes a hole
at an end spaced from the end that is rotatably mounted to the
workstation engaging member.

[0013] The linkage assembly further includes a first connector passing
through the arcuate slot in the first support member, the aligned slots
of the keyboard engaging member, and the hole passing through the second
support member and a second connector passing through the aligned holes
of the keyboard engaging member and the hole of the first support member.

[0014] The braking assembly includes a wedge and a roller assembly. The
wedge is affixed to one side of the keyboard engaging member and includes
a slot aligned with one of the arcuate slots of the keyboard engaging
member. The wedge includes an inclined surface extending rearwardly from
a higher end spaced further outwardly from the keyboard engaging member
side to a lower end. The wedge slot extends along the inclined surface
from near the higher end towards the lower end.

[0015] The roller assembly is carried on the first connector and includes
at least one roller. The roller assembly is biased against the wedge for
adjusting frictional force between the first and second support members,
the further outwardly the roller assembly is urged the greater the
pressure applied by the roller assembly against the wedge and the greater
the frictional force between the first and second support members.

[0016] As the keyboard support surface is pivoted downwardly about the
second connector, the wedge moves rearwardly. The roller assembly roller
rolls along the inclined planar surface from a first unlocked position to
a second locked position. When moving from the first unlocked position to
the second locked position, the roller assembly is urged outwardly with
respect to keyboard engaging member side, thereby applying increased
pressure to the first and second support members to prevent relative
movement between the keyboard engaging member and the workstation
engaging member.

[0017] As the keyboard support surface is pivoted upwardly about the
second connector, the wedge moves forwardly. The roller assembly roller
rolls along the inclined planar surface from the second locked position
to the first unlocked position. When moving from the second locked
position to the first unlocked position, the roller assembly moves toward
the keyboard engaging member side, thereby reducing pressure applied to
the first and second support members and to allow relative movement
between the keyboard engaging member and the workstation engaging member.

[0018] The roller assembly is biased against the wedge by a spring
disposed between the roller assembly and a tilt adjustment knob threaded
onto a threaded end of the first connector. To change an orientation or
tilt angle of the keyboard support surface when the braking assembly is
in the locked position, the keyboard support surface is pivoted slightly
upwardly to a position intermediate a position of the keyboard support
surface when the braking assembly is in the locked position and a
position of the keyboard support surface when the braking assembly is in
the unlocked position to slightly reduce the pressure applied by the
roller assembly against the wedge. The tilt adjustment knob is then
rotated. Rotating the tilt adjustment knob in a counterclockwise
direction reduces a pressure of the roller on the wedge thereby tilting
the keyboard support surface downwardly. Rotating the tilt adjustment
knob in a clockwise direction increases the pressure of the roller on the
wedge thereby tilting the keyboard support surface upwardly. The slight
upward pivoting of the keyboard support surface reduces the frictional
engagement braking forces sufficiently to permit movement of the roller
along the wedge.

[0019] These and other objects, advantages, and features of the exemplary
embodiment of the invention are described in detail in conjunction with
the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] FIG. 1 is a perspective view of an adjustable keyboard support of
the present invention;

[0021] FIG. 2 is an exploded perspective view of the keyboard support of
FIG. 1;

[0022] FIG. 3 is a top plan view of the keyboard support of FIG. 1;

[0023] FIG. 4 is a front elevation view of the keyboard support of FIG. 1;

[0024] FIG. 5 is a side elevation view of the keyboard support of FIG. 1;

[0025] FIG. 6 is a perspective view of a braking assembly of the keyboard
support of FIG. 1;

[0026] FIG. 7 is a front elevation view of the braking assembly of FIG. 6;

[0027] FIG. 8 is a top plan view of the braking assembly in the locked or
braking position;

[0028] FIG. 9 is a sectional view of the braking assembly in the braking
position;

[0029] FIG. 10 is a top plan view of the braking assembly in the unlocked
or non-braking position;

[0030] FIG. 11 is a sectional view of the braking assembly in the
non-braking position;

[0031] FIG. 12A is a perspective view of a tilt lockout member of the
keyboard support of FIG. 1 in a position allowing positive tilt of the
keyboard engaging member;

[0032] FIG. 12B is a side elevation view of an arm of the tilt lockout
member in a position allowing positive tilt of the keyboard engaging
member;

[0033] FIG. 13A is a perspective view of the tilt lockout member in a
position restricting positive tilt of the keyboard engaging member;

[0034] FIG. 13B is a side elevation view of an arm of the tilt lockout
member in a position restricting positive tilt of the keyboard engaging
member;

[0035] FIG. 14A is a top perspective view of the tilt lockout member;

[0036] FIG. 14B is a bottom perspective view of the tilt lockout member;

[0037] FIG. 15 is a section view of the keyboard support depicting a left
side counterbalance torsion spring;

[0038] FIG. 16A is a section view of the keyboard support depicting a
right side counterbalance torsion spring in a maximum torsion position;

[0039] FIG. 16B is a section view of the keyboard support depicting the
right side counterbalance torsion spring in an intermediate torsion
position;

[0040] FIG. 16C is a section view of the keyboard support depicting the
right side counterbalance torsion spring in a minimum torsion position;

[0041] FIG. 17 is a top plan view of a tilt indicator assembly of the
keyboard support of FIG. 1;

[0042] FIG. 18 is bottom plan view of the tilt indicator assembly;

[0043] FIG. 19 is a section view of the tilt indicator assembly as seen
from a plane indicated by the cut line 19-19 in FIG. 18; and

[0044] FIG. 20A is a schematic depiction of a four bar parallelogram
linkage of the tilt indicator assembly when a keyboard engaging member is
in a negative tilt position; and

[0045] FIG. 20B is a schematic depiction of the four bar parallelogram
linkage of the tilt indicator assembly when a keyboard engaging member is
in a positive tilt position.

DETAILED DESCRIPTION

[0046] FIG. 1 depicts a keyboard support 10 constructed in accordance with
one exemplary embodiment of the present invention. The support 10 is
intended to position a keyboard 12 with respect to a workstation such as
a desk 14 (both shown in dashed line in FIG. 1). The support 10 includes
a keyboard engaging member 20 movably coupled to a workstation engaging
member 40 by a linkage assembly 60. The support 10 additional includes a
braking assembly 80 to lock the keyboard engaging member 20, and thereby
the keyboard 12, in a desired position with respect to the workstation
engaging member 40 and to unlock or permit movement of the keyboard
engaging member 20 with respect to the workstation engaging member 40.

[0047] For ease of description, but not by way of limitation, a forward
direction will be presumed to be a horizontal direction H toward a user
of the keyboard 12, a rearward direction will be opposite the forward
direction. Outward to the right will mean a horizontal direction away
from a centerline C-C through the support 10 to the user's right (shown
as HR in FIG. 1), outward to the left will be opposite outward to the
right (shown as HL in FIG. 1). Upward will be vertically upward (shown as
V in FIG. 1), downward will be opposite upward.

[0048] The keyboard engaging member 20 (best seen in FIGS. 2, 3, 5 and
12A) includes a keyboard support surface 22 comprising two spaced apart,
generally planar keyboard support surfaces 22a, 22b extending above a
center section 24. The support surface 22 supports a planar keyboard rest
26 (shown in dashed line in FIG. 1) on which the keyboard 12 is disposed.
The keyboard engaging member 20 also includes a pair of side pieces 28a,
28b which extend rearwardly from the center section 24 and are oriented
vertically. The respective side pieces 28a, 28b each include a pair of
rearwardly extending fingers 30, 31 that define an engagement between the
keyboard engaging member 30 and the linkage assembly 60. The fingers 30,
31 are generally coplanar with the side pieces 28a, 28b. The finger 30
includes an arcuate slot 32 and the finger 31 includes an aperture or
hole 32 disposed vertically above the slot 32. The side pieces 28a, 28b
also each include four small apertures 34 surrounding the slot 30 sized
to receive legs 81 of a wedge 82 of the braking assembly 80

[0049] The workstation engaging member 30 (best seen in FIGS. 2, 3 and 4)
includes a U-shaped clevis bracket 32 and flange 34 secure the keyboard
support 10 to an underside 16 of a desk 14. The flange 34 is affixed to
the desk underside 16 with four screws. Obviously, one of skill in the
art would recognize that there are other methods of affixing the
workstation engaging member 30 to the desk underside 16.

[0050] A spin rivet 36 extends through aligned openings in the bracket 32
and an upper planar surface 38 of the bracket 32 to rotatably affix the
bracket 32 to the flange 34. This allows the keyboard support 10 to be
pivoted about the rivet 36 to either the left or right side of the user,
if desired. It should also be noted that instead of the flange 34 being
mounted directly to the underside 16 of the desk 14, if desired the
flange 34 may be part of a carriage having ball bearing slides which
slide within tracks of a housing affixed to the underside 16 of the desk
as disclosed in the '467 patent to Timm referenced earlier. Alternately,
instead of ball bearing slides, the carriage may utilize polymer slide
bearings.

[0051] The linkage assembly 60 (best seen in FIGS. 2, 5, 6 and 10) permits
the keyboard engaging member 20 to be moved vertically upward and
downward with respect to the workstation engaging member 40 and with
respect to an orientation or tilt angle A (FIG. 5) of the keyboard 12.
The tilt or angle of inclination of the keyboard 12 is positive if the
keyboard or keyboard support surfaces 22a, 22b are tilted toward a user
and negative if the keyboard 12 is tilted away from the user. Moving the
keyboard engaging member 20 vertically changes a height of the keyboard
12 with respect to the working upper surface 16 of the desk 14.

[0052] The linkage assembly 60 includes a lower bracket 62 and a pair of
upper supports or arms 64a, 64b all pivotally supported by the downwardly
extending supports 48a, 48b of the workstation engaging member 40. The
supports 48a, 48b define the engagement between the workstation engaging
member 40 and the linkage assembly 60.

[0053] At a rearward end, the upper pair of support arms 64a, 64b include
aligned openings 68 that accommodate a bearing in the form of a rod 69
that is received in aligned openings 49 of the downwardly extending
supports 48a, 48b. The upper support arms 64a, 64b pivot about the rod
69. A spring counterbalance assembly 100 (described below) includes a
pair of counterbalance springs 102, 104 (described below) disposed around
the rod 69 to assist the user in raising the keyboard engaging member 20.
The rod 69 also supports a protective cover 78 that slides along the
upper planar cross piece 67a of the lower bracket 62. The cover 78 helps
to keep dirt and debris from the counterbalance assembly and also
provides a pleasing aesthetic appearance.

[0054] The lower bracket 62 is rectangular in cross section and defines
two lower support arms 66a, 66b bridged by top and bottom planar cross
pieces 67a, 67b. The lower support arms 66a, 66b of the lower bracket 62
also define openings 70 that accommodate a bearing in the form of a
second rod 74 that is also attached to the downwardly extending supports
48a, 48b.

[0055] At a forward end of the upper pair of support arms 64a, 64b, the
arms include tabs 71 that define arcuate slots 72 and openings 73. A
bearing rod or connector 74 extending through the openings 73 of the pair
of elongated arms 64a, 64b and the openings 33 in the fingers 31 of the
keyboard engaging member 20 to pivotally connect the keyboard engaging
member 20 and the upper support arms 64a, 64b to allow relatively
unrestricted relative rotation between the keyboard engaging member 20
and the workstation engaging member 40. A threaded bearing rod 75 extends
through arcuate slots 32 in fingers 30 of the keyboard engaging member 20
and arcuate slots 72 in tabs 71 of the pair of upper elongated arms or
supports 64a, 64b.

[0056] The angle between the workstation engaging member 40 and the pair
of upper supports 64a, 64b and the pair of lower supports 66a, 66b
determines the height of the keyboard 12 in relation to the desk 14. The
angle between the workstation engaging member 40 and the upper and lower
supports 64a, 64b, 66a, 66b is, in turn, determined by the position of
threaded rod 75 along the arcuate slots 72. The workstation engaging
member 40 extends away from the desk 14 in a direction generally parallel
to the desk top or work surface 16. This corresponds to a maximum
keyboard height adjustment for the support 10.

[0057] Braking Assembly 80

[0058] The braking system or assembly 80 provides for a locked condition
and an unlocked condition. In the locked condition, the linkage assembly
60 is fixed such that there is no relative movement of the keyboard
engaging member 20 with respect to the workstation engaging member 40. In
the unlocked condition, the linkage assembly moves or pivots so as to
allow relative movement of the keyboard engaging member 20 with respect
to the workstation engaging member 40.

[0059] As can best be seen in FIGS. 6-11, one exemplary embodiment of the
braking system 80 of the present invention includes the wedge 82 and a
roller assembly 83 including a pair of rollers 84a, 84b. In one preferred
embodiment, the rollers 84a, 84b are mounted on a pair of axles 84c, 84d
extending from opposite ends of a hub or body 89 of the roller assembly
83 (only a top one of the axles 84c cab be seen in FIG. 2). The rollers
84a, 84b are solid metal rollers which are in direct contract with the
axles 84c, 84d and a bearing surface of the wedge 82. An inner bore of
the respective rollers 84a, 84b functions as an integral plane bearing.
The wedge 82 is affixed to an outer surface of the finger 30 of the
keyboard engaging member right hand side piece 28a. Specifically, the
wedge 82 includes a pair of legs which fit into two small apertures 34 in
the side piece finger 30.

[0060] The roller assembly 83 is slidably mounted on the threaded rod 75
and is biased inwardly to contact the wedge 82 by a bias spring 85
disposed between a flat bearing surface 86 of a tilt adjustment knob 87
and a stepped portion 88 of the hub 89 of the roller assembly 83. The
bias spring 85 serves to hold the roller assembly 83 against the wedge 82
when the braking system 80 is in a disengaged or unlocked position. A hex
head 76 of the threaded rod 75 bears against the finger 30 of the left
hand side piece 28b. The tilt adjustment knob 87 includes internal
threads 90 which are threaded onto a threaded distal end 77 of the rod
75. The wedge 82 includes an arcuate opening 91 which is aligned with the
arcuate slot 32 in the right side piece finger 30. The wedge 82 increases
in thickness moving from back 82a to front 82b. The rollers 84a, 84b are
constrained to roll along an outer surface 92 of the wedge 82 and, more
specifically, along a path of travel on the outer surface 92 adjacent the
arcuate opening 91 of the wedge 82 because the threaded rod 75 extends
through the arcuate opening 91.

[0061] A position of the rollers 84a, 84b on the outer surface 92 of the
wedge 82 determines the force applied by the flat bearing surface 86 of
the tilt knob 87 to the roller assembly hub 89 (FIG. 9) and thereby the
force applied by the rollers 84a, 84b against the wedge 82. The force
applied by the rollers 84a, 84b against the wedge 82 determines, in turn,
the frictional engagement force between the upper support arms 64a, 64b,
the lower support arms 66a, 66b and the side pieces 28a, 28b of the
keyboard engaging member 20. More specifically, the frictional engagement
between an outer surface of a forward end portion (including the tabs 71)
of the upper support arms 64a, 64b and an inner surface of the pair of
fingers 30, 32 extending from the side pieces 28a, 28b of the keyboard
engaging member 20 and between an inner surface of the forward end
portion of the upper support arms 64a, 64b and an outer surface of a
forward end portion the lower support arms 66a, 66b of the bracket 62.

[0062] The roller position with respect to the wedge 82 can best be seen
in the views shown in FIGS. 8-11. In FIGS. 8 and 9, the braking position
of the braking assembly 80 is shown. As can be seen the threaded rod 75
is near a forward end 91b of the wedge arcuate opening 91. In this
braking position, the wedge 82 is thicker, forcing the roller assembly 83
outwardly to the right along the threaded rod 75 and thereby compressing
the spring 85 to the point that an end 94 of the roller assembly hub 89
contacts the bearing surface 86 of the tilt assembly knob 87.

[0063] In this braking position, the frictional engagement force between
the outer surface of forward end portion of the upper elongated support
arms 64a, 64b and the inner surface of the pair of fingers 30, 32
extending from the side pieces 28a, 28b of the keyboard engaging member
20 and between the inner surface of the forward end portion of the upper
support arms 64a, 64b and the outer surface of a forward end portion the
two lower support arms 66a, 66b of the bracket 62 is sufficient to
prevent the keyboard engaging member 20 from pivoting with respect to the
bearing rod 74. There is also a braking force generated by the contact of
the rollers 84a, 84b to the contact surface 93 of the wedge 82 because a
contact angle between the rollers 84a, 84b and the wedge 82 functions to
oppose relative movement of the rollers 84a, 84b along the wedge 82.
Since the upper support arms 64a, 64b and the lower supports arms 66a,
66b cannot move with respect to each other, the keyboard engaging member
20 is locked in position with respect to the workstation engaging member
40, thus, the braking assembly 80 is in the locked condition.

[0064] In FIG. 11, a nonbraking position of the braking assembly 80 is
shown. As can be seen the threaded rod 75 is at or near the rearward end
91a of the wedge arcuate opening 91. In this nonbraking position, the
thickness of the portion of the wedge 82 contacted by the rollers 84a,
84b is reduced compared to the braking position. The roller assembly hub
89 is not moved outwardly to the right as much as in the braking position
and the biasing spring 85, therefore, is less compressed. The frictional
engagement force is reduced between the upper and lower support arms 64a,
64b, 66a, 66b. In the nonbraking position, the frictional engagement
force between the upper support arms 64a, 64b, the lower support arms
66a, 66b, and the side pieces 28a, 28b of the keyboard engaging member 20
is reduced such that the keyboard engaging member 20 pivots with respect
to the bearing rod 74. Since the upper support arms 64a, 64b and the
lower support arms 66a, 66b can move with respect to each other, the
keyboard engaging member 20 is movable with respect to the workstation
engaging member 40.

[0065] It should be noted, however, that an any position of the rollers
84a, 84b along the wedge outer surface 92, including the position shown
in FIGS. 10 and 11, if the tilt adjustment knob 87 is turned sufficiently
in the clockwise direction (as viewed in FIG. 5), that is, the tilt knob
87 being threaded further onto the rod 75, it will cause the biasing
spring 85 to compress, and ultimately enough force will be applied by the
flat bearing surface 86 of the tilt knob 87 to the roller assembly hub 89
to cause the braking system 80 to be in a braking position, that is, the
keyboard engaging member 20 will be locked with respect to the
workstation engaging member 40, thus, the braking assembly 80 is in the
locked condition.

[0066] A downward pressure on the keyboard engaging member 20 and
specifically the front portion 20a, tends to rotate the keyboard support
surfaces 22a, 22b in a counterclockwise direction (shown as CC in FIG.
5). This moves the wedge 82 rearwardly with respect to the threaded rod
75 and the roller assembly 83. As the wedge 82 moves rearwardly, the
rollers 84a, 84b turn and a thickness of the portion of the wedge
directly under the rollers 84a, 84b increases. This urges the roller
assembly 83 outwardly along the threaded rod 75 increasing the
compression of the spring 85 and the frictional engagement force between
the upper and lower supports 64a, 64b, 66a, 66b and the sidepieces 28a,
28b of the keyboard engaging member 20 and, ultimately, moves the braking
assembly 80 to the braking position. This self locking feature of the
braking system 80 prevents unintended downward motion of the keyboard
engaging member 20. To adjust the height of the keyboard support surfaces
22a, 22b, the user rotates the keyboard engaging member 20 about the rod
74 in an upward direction (clockwise--shown as CW in FIG. 5) by lifting
upwardly on the front portion 20a of the keyboard engaging member 20 to a
tilt angle about -23.degree.. Rotating the keyboard support surfaces 22a,
22b in a clockwise direction moves the wedge 82 forwardly with respect to
the threaded rod 75 and the roller assembly 83. As the wedge 82 moves
forwardly, the rollers 84a, 84b turn on the wedge and the thickness of
the portion of the wedge directly under the rollers 84a, 84b decreases.
The bias spring 85 urges the roller assembly 83 inwardly along the
threaded rod 75. When the flat bearing surface 86 of the tilt knob 87
disengages or no longer contacts the roller assembly hub 89, the braking
assembly 80 is in the unlocked condition and the frictional engagement
force between the upper and lower support arms 64a, 64b, 66a, 66b and the
sidepieces 28a, 28b of the keyboard engaging member 20 is sufficiently
decreased to permit relative movement of the keyboard engaging member 20
with respect to the workstation engaging member 40 and thereby allow the
height of the keyboard rest 26 to be adjusted.

[0067] Even during the unlocking procedure, the bias spring 85 maintains
some pressure on the roller assembly 83 so that the rollers 84a, 84b do
not slip off or away from their path of travel along the periphery 93 of
the wedge outer surface 92 adjacent the arcuate opening 91. Further,
since the roller assembly hub 89 is rotatable coaxially with respect to
the threaded rod 75, the rollers 84a, 84b exhibit a swiveling castor
effect to insure that the rollers are aligned with respect to the wedge
opening 91. When the user releases the keyboard engaging member 20, the
rollers 84a, 84b roll forwardly along the wedge 82 providing increased
frictional engagement between the upper and lower support arms 64a, 64b,
66a, 66b and the sidepieces 28a, 28b of the keyboard engaging member 20
to lock the height of the keyboard engaging member 20. Movement of the
rollers 84a, 84b with respect to the surface of the wedge 82 is
approximately 0.9 inches laterally along the bearing face 93 of the wedge
82 and less than 0.1 inches axially along the rod 75 in moving between
the locking and non-locking positions which is a result of a clearance
space between the flat bearing surface 86 of the tilt knob 87 to the
roller assembly hub 89 collapsing when going from a unlocked condition to
a locked condition.

Tilt Adjustment of Keyboard Engaging Member 20

[0068] The tilt adjusting knob 87 (best seen in FIGS. 8, 9, 10 and 11), in
conjunction with the braking assembly 80 allows the user to control the
tilt angle of the keyboard engaging member 20. The knob 87 is threaded
onto the threaded rod 75 thereby trapping the bias spring 85 between the
knob 87 and the stepped surface 88 of the roller assembly hub 89. When
the braking assembly 80 is in an unlocked condition, by rotating the knob
87 clockwise or counterclockwise, the user can change an angle of tilt
from a present position of the keyboard support surface 22a, 22b with
respect to the rod 74. Looking at FIG. 5, from a given position, if the
keyboard support surface 22a is rotated about the rod 74 in a clockwise
direction CW, the movement is defined to be a negative tilt angle (shown
as -A in FIG. 5) away from the user. If the keyboard support surface 22a
is rotated about the rod 74 in a counterclockwise direction, the movement
is defined to be a positive tilt angle (shown as +A in FIG. 5) toward the
user.

[0069] As the knob 87 is rotated clockwise as viewed from the right hand
side (FIG. 5), the knob is threaded further onto the rod 75, thereby
causing the rollers 84a, 84b to exert greater force on the wedge 84.
Increasing the force on the wedge 84 causes the wedge to move forwardly
(toward the user) thereby decreasing a thickness of the wedge under the
rollers 84a, 84b and accordingly decreasing the force applied by the
rollers to the wedge. The wedge 84 is attached to the keyboard engaging
member 20 and the keyboard engaging member pivots about the rod 74. Thus,
as the wedge 84 moves forwardly (toward the user), the keyboard engaging
member 20 pivots upwardly (or clockwise) about the rod 74 resulting in a
negative angular change in keyboard orientation (see FIG. 5).

[0070] By the same token, as the knob 87 is rotated counterclockwise as
viewed from the right hand side (FIG. 5), the knob is unthreaded from the
rod 75, thereby causing the rollers 84a, 84b to exert less force on the
wedge 84. Because of the weight of the keyboard engaging member 20 and
the keyboard 12 supported thereon, the wedge 84 is biased to move
rearwardly (away from the user). Decreasing the force on the wedge 84
causes the wedge to move rearwardly thereby increasing a thickness of the
wedge under the rollers 84a, 84b and thus increasing the force applied by
the rollers to the wedge until an equilibrium is achieved. Thus, as the
wedge 84 moves rearwardly, the keyboard engaging member 20 pivots
downwardly (or counterclockwise) about the rod 74 resulting in a positive
angular change in keyboard orientation (see FIG. 5). In some instances,
because of the rollers 84a, 84b are not zero friction rollers, the user
may need to press down slightly on a front edge portion 20a of the
keyboard engaging member 20 to facilitate a positive tilt angle change.

[0071] When the braking assembly 80 is in the locked condition, rotation
of the tilt knob 87 in the counterclockwise direction (loosening the
knob) will result in a positive tilt angle change in keyboard
orientation. However, if the braking assembly 80 is in the locked
condition, rotation of the tilt knob 87 in the clockwise direction
(tightening the knob) will increase the frictional engagement forces of
the linkage assembly 60. This will prevent a negative tilt angle change.
In order to effect a negative tilt angle change in keyboard orientation,
the front of the keyboard engaging member 20 would have to be pivoted
upwardly, at least slightly, to somewhat loosen the linkage assembly 60
and thereby permit negative tilt angle change upon clockwise rotation of
the knob 87.

[0072] It should be noted that the braking assembly 80 includes relative
degrees of locking that are intermediate the locked condition and the
unlocked condition. Stated another way, the frictional engagement forces
of the linkage assembly 60 vary depending on the magnitude of force
applied by the flat bearing surface 86 of the tilt knob 87 to the end 94
of the roller assembly hub 89.

Spring Counterbalance Assembly 100

[0073] One exemplary embodiment of a spring counterbalance assembly 100
(best seen in FIGS. 15, 16A, 16B, and 16C) includes the pair of
counterbalance springs 102, 104 disposed around the rod 69 to assist the
user in raising the keyboard support 10. Advantageously, the spring
counterbalance assembly 100 provides for a variable magnitude of spring
torsion which can be changed by the user depending on the magnitude of
counterbalance force desired by the user and the weight of the keyboard
12 being supported by the keyboard engaging member 20. The left spring
102 provides for a constant torsion force, while the right spring 104 can
be engaged with the clevis bracket 42 in a selected one of three
different positions to vary the torsion force between low, medium and
high torsion force.

[0074] The pair of upper support arms 64a, 64b is bridged by a rod 106.
One end 102a of the left spring 102 is hooked under the rod 106, while
the other end 102b of the left spring 102 bears against a bottom surface
50 of the u-shaped clevis bracket 42. The left spring 102 thereby
provides for a torsion which tends to raise or upwardly pivot the
elongated arms 64a, 64b about the rod 69 and thereby raise the keyboard
engaging member 20.

[0075] One end 104a of the right spring 104 is also hooked under the rod
106, while the other end 104b defines a loop 104c with a distal end 104d
insertable into a selected one of three positions corresponding to the
three slotted openings 51a, 51b, 51c in the right side downward support
48a. As seen in FIG. 16C, if the distal end 104d of the right spring 104
is inserted into the vertically highest slotted opening 51a, the spring
torsion applied by the right spring 104 to the rod 106 is the lowest of
the three positions because the spring is more unwound than in any of the
other two positions. Thus, the upward counterbalancing force applied to
the upper support arms 64a, 64b and the keyboard engaging member 20 is
the lowest of the three positions.

[0076] As seen in FIG. 16B, if the distal end 104d of the right spring 104
is inserted into the middle slotted opening 51b, the spring is more wound
up (compared to opening 51a) and the spring torsion applied by the right
spring 104 to the rod 106 is greater. This provides an intermediate
magnitude of counterbalancing force to the upper support arms 64a, 64b
and the keyboard engaging member 20 compared to the other two positions.

[0077] Finally, as seen in FIG. 16A, if the distal end 104d of the right
spring 104 is inserted into the lowest slotted opening 51c, the spring is
wound even more tightly than when the distal end is in opening 51b. This
increases the spring torsion applied by the right spring 104 to the rod
106 to a maximum level and, therefore, the counterbalancing force applied
to the upper support arms 64a, 64b and the keyboard engaging member 20 is
a maximum level of the three positions.

Tilt Lockout Member 120

[0078] Depending upon the size and shape of specific keyboard 12 selected
by the user and the seating arrangement used by the user, under certain
conditions it may be ergonomically advantageous to prevent too great a
positive tilt of the keyboard support surface 22. Additionally, too great
a positive tilt may result in the keyboard accidentally sliding off of
the keyboard rest 26. Accordingly, a tilt lockout member 120 is provided.
As can best be seen in FIGS. 12A, 12B, 13A, 13B, 14A, and 14B, the tilt
lockout member 120 fits over the hex-headed end 76 of the threaded rod 75
and slides on the rod. It should be noted that other shapes besides
hexagonal may be used for the rod end 76 provided the shape provides a
bearing surface for the tilt lockout member 120.

[0079] The lockout member 120 is adapted to be pivoted between a lockout
position and a non-lockout position. An opening 122 of the tilt lockout
member 120 receives the hex-headed end 76 of the rod 75 and a shoulder
124 of the tilt lockout member prevents the tilt lockout member from
falling off the hex-headed end 76. The lockout member 120 includes an
inwardly extending arm 126 which is adapted to extend into the arcuate
slot 32 of the left side finger 31.

[0080] When tilt lockout member 120 is positioned with respect to the rod
75 such that the arm 126 extends into the arcuate slot 32 forwardly
(toward the user) of the rod, as seen in FIGS. 13A and 13B, the tilt
lockout member 120 is in the tilt lockout position and the usable angle
of tilt of the keyboard engaging member 20 is limited to 0.degree. to
-15.degree. using the adjustment knob 87. That is, positive tilt is
locked out. The reason that the positive tilt angle is limited to
0.degree. is that, as noted above, the arm 126 extends into the arcuate
slot 32 forwardly of rod 75. Thus, the keyboard support member 40 cannot
be pivoted downwardly beyond a tilt angle of 0.degree. because at
0.degree., a forward edge of the slot 32, that is, a left side of the
slot 32 as viewed in FIG. 13B, is in contact with the arm 126 and further
positive tilt is precluded. Advantageously, if unlocking of the braking
assembly 80 is desired, this can still be accomplished with the tilt
lockout member 120 in the tilt lockout position or the non lockout
position simply by lifting a front edge of the keyboard engaging member
20 to a tilt angle of -23.degree. to disengage the brake. As can be seen
in FIGS. 12A and 12B, when the tilt lockout member 120 is positioned with
respect to the rod 75 such that the arm 126 extends into the arcuate slot
32 rearwardly of the rod 75, the tilt lockout member 120 is in the non
lockout position and the angle of tilt of the keyboard engaging member 20
will vary (by rotation of the tilt knob 87) between +10.degree. and
-15.degree..

[0081] To move the tilt lockout member 120 from one position to the other,
the tilt knob 87 is sufficiently loosened, such that a distance between
tilt lockout member 120 and the finger 31 is sufficient to allow the arm
126 of the tilt lockout member 120 clear the arcuate slot 32 which is
achieved by pulling on the tilt lockout member 120 outward to the left
(shown as HL in FIG. 1) against the force of the bias spring 85. Then the
tilt lockout member 120 is rotated with the hex head 76 of the rod 75
appropriately to either the lockout or non lockout position, as desired.

[0082] To make it easier for the user to determine whether the tilt
lockout member 120 is in the lockout position or the non-lockout
position, the tilt lockout member 120 includes a raised peripheral
portion 128 with indicia. When the raised peripheral portion 128 is
oriented upwardly (FIG. 13A), the tilt lockout member 120 is in the
lockout position. When the raised peripheral portion 128 is oriented
downwardly (FIG. 12A), the tilt lockout member 120 is in the non-lockout
position.

Tilt Gauge Assembly 140

[0083] The keyboard support of the present invention includes a tilt gauge
assembly 140 which provides the user an easily readable indication of the
current tilt angle of the keyboard 12. As can best be seen in FIGS. 17,
18, 19, 20A and 28B, one exemplary embodiment of the tilt gauge assembly
140 includes a cover 142 and a parallelogram linkage 144 affixed thereto.
The cover 142, in addition to supporting the parallelogram linkage 144,
protects the linkage assembly 60 from debris and presents an attractive
appearance to the assembled keyboard support 10.

[0084] The cover 142 is sized to fit firmly in position over the side
pieces 28a, 28b of the keyboard engaging member 20 and includes a pair of
forwardly extending ears 146 extending from opposite sides of the cover
which fit snugly against the side pieces 28a, 28b and under the rearward
portion of the keyboard support surfaces 22a, 22b. A J-shaped hook 148
extends downwardly from an inner surface 150 of a top side 152 the cover
142 and snap fits over the rod 74 to hold the cover in place.

[0085] The parallelogram linkage 144 includes a base 154 that is anchored
to and extends through a slotted opening 156 in a front side 158 of the
cover 142. Extending from the base are spaced apart horizontal beams, a
bottom beam 162 and a top beam 164. The bottom beam 162 comprises a lower
portion 174 of a stationary member 166 and a lower portion 176 of an
offset movable member 168 coupled by a lower pivot member 170. The
stationary member 166 is stationary with respect to the base 154, while
the movable member 168 is movable with respect to the base 154. The top
beam 164 comprises an upper portion 178 of the stationary member 166 and
an upper portion 180 of the movable end member 168 coupled by an upper
pivot member 172.

[0086] The lower pivot member 170 is pivotally connected by a hinge at one
end to the lower portion 174 of the stationary member 166 and is
pivotally connected by a hinge at an opposite end to the lower portion
176 of the movable end member 168. The upper pivot member 172 is
pivotally connected by a hinge at one end to the upper portion 178 of the
stationary member 166 and is pivotally connected by a hinge at an
opposite end to the upper portion 180 of the movable end member 168.

[0087] A rearward face 182 of the movable end member 168 abuts and bears
against the threaded rod 75. A biasing spring 184 coupled to a
horizontally extending arm 186 of the upper pivot member 172 biases the
movable end member 168 rearwardly against the threaded rod. As the planar
keyboard support rest 26 of the keyboard engaging member 20 is tilted
with respect to the desk 14, the workstation engaging member 40 and the
threaded rod 75 remain stationary. Since the stationary member 166 is
mounted to the cover 142 and since the cover is mounted to the keyboard
engaging member 20, the stationary member 166 pivots with the keyboard
engaging member 20 about the rod 74. However, the movable end member 168
abuts the threaded rod 75. The threaded rod 75 does not move when the
tilt angle of the keyboard engaging member 20 is changed. The movable end
member 168 slides and rotates relative to the threaded rod 75, however,
the movable end member 168 remains tangent to the cylindrical outer
surface of the threaded rod 75 at all times. Thus, a dynamic line of
contact between the movable end member 168 and the threaded rod 75 does
not move radially forward or rearward with respect to the rod 75.
Accordingly, changing the angle of tilt of the keyboard engaging member
20 causes a distance between the stationary member 166 and the movable
end member 168 (along a longitudinal axis L-L of the parallelogram 144)
to change. Changing the distance between the stationary member 166 and
the movable end member 168 causes the upper and lower pivot members 172,
170 to pivot on their respective hinges.

[0088] Extending from the upper pivot member 172 is an upwardly angled arm
188 terminating in a pointer needle 190. The pointer needle 190 extends
through a slotted opening 192 in the top side 152 of the cover 142. As
the tilt angle of the keyboard engaging member 20 changes, as explained
above, due to the geometry of the parallelogram linkage 144, the upper
pivot member 172 pivots (as does, of course, the lower pivot member 170).
As the upper pivot member 172 pivots, the pointer needle 190 moves along
the arcuate slotted opening 192. Tilt angle indicia 194 are printed along
an edge of the slotted opening 192 to indicate the angle of tilt. To read
the tilt angle, the user merely glances at the position of the pointer
needle 190 and reads the value from the indicia 194 that is aligned with
the pointer needle 190. The value of indicia aligned with the needle 190
corresponds to the present tilt angle of the keyboard engaging member 20.
Basically, the tilt gauge assembly 140 converts the longitudinal movement
of the movable end member 168 resulting from contact with the threaded
rod 75 as the tilt angle is changed into an angular deflection of the
needle 190.

[0089] It is appreciated that while a preferred embodiment of the
invention has been described, it is the intent that the invention include
all modifications and alterations from the disclosed design falling
within the spirit or scope of the appended claims.